Expression of the α-smooth muscle actin–green fluorescent protein (αSMA–GFP) transgene in dental follicle and periodontal ligament. αSMA–GFP expression was evaluated in decalcified frozen sections of mandibles derived from 3–5-d-old neonatal mice (A, B) and from 4-wk-old αSMA–GFP transgenic mice (C–F). Epifluorescence was detected in cells within the dental follicular area of the developing tooth and in the outer dental epithelium (A). The perivascular (PV) area in the apical part of the root showed intense expression of GFP (C, E, see arrows). Green fluorescent protein was also detected in a few cells within the dental pulp (E, arrowheads). Hematoxylin & eosin staining of adjacent sections are shown in panels B, D and F. Images were taken at 10× (A–D) and 20× (E, F) magnifications (bar = 100 μm).